Short answer - you don't. I've flown from boats a handful of times, and it's stressful. When I started, I would ask them to keep the boat as still as possible,

Short answer - you don't. I've flown from boats a handful of times, and it's stressful. When I started, I would ask them to keep the boat as still as possible, hover next to the boat, then slowly move over to me so I could reach it. Grab it from underneath and flip it over to kill the motors. That's obviously not safe, and it's not hard to find photos in drone groups of people's hands after a failed attempt to do exactly this. It's not pretty. After that I came across an old indoor practice goal for soccer players - basically a net on a stand. I modified it to lay flat and started using it. I'd get the quad close to the boat, hover a couple of feet over the net, and kill the motors. It worked, but felt like I was risking my quad dropping into the ocean every time I did it. These days I've gone back to hand-catching, but with a vertical grip that I mounted under the aircraft. I 3D printed a "harness" of sorts that fits around the fuselage and has a Picatinny rail on the bottom (like on a rifle). I picked up a cheap vertical grip designed for a gun that I can quickly mount on the rail - it extends ~6" below and gives me something to grab without being on the same plane as the props. It works well enough, but isn't perfect. It would interfere with the field of view on something with a 360º camera gimbal (like an Inspire), and has a significant impact on flight time and performance even though I did all I could to reduce the weight.